The scene of a courthouse shooting in Kaufman, Texas. / KDFW

by John Bacon and William M. Welch, USA TODAY

by John Bacon and William M. Welch, USA TODAY

A manhunt was underway for two suspects after an assistant district attorney was gunned down Thursday outside a courthouse in North Texas.

Mark Hasse, 57, was walking from a parking lot toward the Kaufman County Courthouse annex when he was shot multiple times just before 9 a.m., Kaufman County sheriff's department spokeswoman Pat Laney said.

Laney said late Thursday that no arrests had been made in the case. She said earlier reports of an arrest were in error. The Dallas Morning News had reported that Dallas County District Attorney Craig Watkins said he understood there had been an arrest.

Investigators were talking to witnesses and had some leads but had not arrested anyone as of Thursday afternoon, Kaufman Police Chief Chris Aulbaugh said.

Hasse headed many county drug and murder cases. Shortly after the shooting, Sheriff David Byrnes said the killing was an attack on the criminal justice system."This is the next level (of crime)," he said.

District Attorney Mike McLellan called Hasse's death a "devastating loss" and vowed to prosecute those responsible. He called Hasse a spectacular prosecutor who would not be easily replaced.

McLellan said the prosecutor had worked in a variety of areas including organized crime, knew the dangers of his job and readily accepted them. He was in Kaufman County three years.

Security officers and deputies closed nearby streets in Kaufman, a North Texas town of about 6,700 residents less than 40 miles from Dallas. Kaufman schools were put on lockdown.

Hasse's death raises the larger issue of security for prosecutors who are responsible sending criminals to prison, Dallas County District Attorney Craig Watkins said.

Watkins says he's most concerned that people who are out on bail and awaiting trial will target him as the face of the office or his prosecutors.

"These are people who are on the front line," said Watkins, who leads an office of 250 prosecutors. "Why isn't there security? We have a lot of individuals who have ill will toward our profession. Maybe this unfortunate circumstance will provide a wakeup call for those individuals who do hold the purse strings to make sure we're protected."

Hasse began his career as a prosecutor in Dallas County in 1982 after graduating from Southern Methodist University's law school. He worked as a prosecutor in Dallas until 1988, Watkins said. Although Watkins did not know Hasse, he said he had a reputation as a "very thorough and tough prosecutor."

Lawyer James Lee Bright told the Morning News he arrived at the courthouse just as officers began swarming the scene.

"Within two or three minutes, the whole square was literally flooded with officers," Bright said. He said he saw a woman shaking as she told a bailiff she had witnessed the shooting.

People were allowed to leave the building in groups, depending on where they were parked, he told the Morning News.

"When you hear a DA at 8:40 in the morning is gunned down by two people, I think there's a reasonable presumption that it's not random," Bright said.

Kaufman County Judge Bruce Wood said the courthouse remained closed and it would be up to the sheriff to determine when it would reopen.

Wood told the Morning News he saw Hasse every day in the courthouse hallways.

"He was revered and he did an outstanding job," Wood said. "We see each other every day. â?¦ It's a very small courthouse."

"It's a horrible situation," Wood told the Morning News. "None of us would have ever expected anything like this to ever happen in our county."

The Morning News is reporting that "authorities with knowledge of the assistant DA's caseload say he had been heavily involved in the investigation of members of the Aryan Brotherhood."

The shooting took place hours before two members of the Aryan Brotherhood of Texas pleaded guilty in Houston to racketeering and other charges. The pleas were part of a wide-ranging investigation that included the Kaufman County District Attorney's office.

A probe is underway to determine if the shooting is connected to that investigation, the Morning News says.

The U.S. Justice Department announced those guilty pleas in a statement released Thursday.

The statement claims the brotherhood "enforced its rules and promoted discipline among its members, prospects and associates through murder, attempted murder, conspiracy to murder, arson, assault, robbery and threats against those who violate the rules or pose a threat to the enterprise. Members, and oftentimes associates, were required to follow the orders of higher-ranking members, often referred to as 'direct orders.'"

The Morning News says Hasse was chief of the Dallas County district attorney's organized-crime section from 1985 until 1988 and a former president of the Dallas chapter of Mothers Against Drunk Driving.

In 1995, he suffered a skull fracture when his small plane crashed in Luray, Va. The Morning News says Hasse was flying the lead plane in "Freedom Flight America," a cross-country convoy of hundreds of planes commemorating the end of World War II. He was flying at AT-6 Texan, a World War II-era training aircraft.

His death led to warnings elsewhere. WFAA-TV in Dallas reports that the email below was sent by the Dallas County DA to his staff:

"This message is not intended to scare anyone but please be advised. A Kaufman County prosecutor was fatally shot a few minutes ago outside the Kaufman County Courthouse in Kaufman. Two masked gunmen are the suspects. They have not been apprehended yet.

Please be aware of your surroundings when leaving the building for your safety. This is probably an isolated incident but until further notice if you plan to work past dark today please be careful and ask security for assistance escorting you to your vehicles if needed. I will keep you informed as to the arrest of the suspects when I am notified. Don't panic but please be aware of your environment when leaving the building."

Kaufman Police Chief Chris Aulbaugh said the shooting would have a major impact on Kaufman.

"Any loss of life, especially someone out there protecting the community, would have that effect," he said.